[ Chinese wardrobe network ] The use rate of the fume hood in the laboratory construction is very high. How to choose the appropriate and reasonable installation position of the fume hood, the type, material and shape of the fume hood should be selected according to the experimental content, and ventilation should be considered.
The fume hood is an integral part of the laboratory ventilation design. In order to prevent laboratory workers from inhaling or ingesting some toxic, pathogenic or toxic chemicals and organisms, there should be good ventilation in the laboratory. Here are some of the features of the fume hood.
First, the function
1. Release function: It should have the means to absorb the harmful gas generated inside the fume hood by absorbing the gas outside the cabinet, and dilute it to exclude the outdoor mechanism.
2. Non-backflow function: It should have the function of the airflow generated by the exhaust fan inside the fume hood to prevent harmful gas from flowing into the room from the inside of the fume hood. To ensure the realization of this function, a fume hood and a ventilation The method of connecting the machine with a single pipe cannot be connected by a single pipe, and is only limited to the same room in the same floor, and the fan is installed at the end of the pipe as much as possible [or at the top of the layer.
3. Isolation function: The inside of the fume hood should be separated by a non-sliding glass window.
4. Supplementary function: There should be a passage or an alternative device for taking in fresh air from outside the fume hood when harmful gases are exhausted.
5. Control wind speed function: In order to prevent the harmful gas in the fume hood from escaping, it is necessary to have a certain suction speed. The factors that determine the suction speed of the air inlet of the fume hood are: the heat generated by the experimental content and the relationship with the number of air changes. The nature of the experiment and the nature of the hazardous materials. The national standard stipulates that the surface wind speed of the fume hood is 0.5 m / s ± 10%. In order to ensure such wind speed, the exhaust fan should have the necessary static pressure, that is, when the air passes through the ventilation pipe. Frictional resistance. When determining the wind speed, you must also pay attention to the noise problem. When the air flows through the pipe, it is limited to 7-10m. If it exceeds 10m, noise will be generated. Generally, the laboratory (indoor background noise level) noise limit
6. Heat and acid and alkali corrosion: There are some electric furnaces in the fume hood, and some experiments produce a large amount of toxic and harmful gases such as acid and alkali, which are extremely corrosive. The countertops, linings, side panels and selected water nozzles and air nozzles of the fume hood should have anti-corrosion function. In the experimental use of strong acid materials, the overall material of the fume hood must be protected against acid and alkali, and must be made of stainless steel or PVC material.
Second, the use of maintenance
1. In the course of the experiment, the experimental device for generating harmful substances shall be placed at a place where the operating port of the cabinet of the fume hood is greater than 150 MM to prevent the spillage of harmful substances;
2. The experimental device of the fume hood should not obscure the exhaust slit;
3. After the experiment is completed, the fan should not be turned off immediately, and it will take 3~5 minutes to turn off;
4. The fume hood should not be used as a storage cabinet;
5. The inside of the fume hood should always keep the inner surface of the cabinet clean and sealed. It should be thoroughly cleaned and cleaned regularly. If it is damaged, it must be repaired in time;
6. Fans, ducts and related accessories should be regularly inspected.
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